Constructing worlds Flashcards
What does retinotopic reffer to?
That visual organisation relates to where things are occuring in visual space. Light falling on a particular part of our retina.
What is largely responsible for conscious visual experience?
The retinogeniculate pathway.
What is the difference between the retinogeniculate pathway and the LGN?
Retinogeniculate pathway: a pathway responsible for transmitting visual signals from the eyes to the primary visual cortex (inclues LGN).
Lateral Geniculate Nucleus: specific structure within the thalamus. serves as a relay station for visual information traveling from the retina to the primary visual cortex. Organized into six layers,
What does the binocular visual feild allow for?
Locate objects in depeth.
How could you describe our visual processing arragement?
As contralateral. Opposite side processing.
What would occur with a unilateral lesion (left) of the primary visual cortex?
Loss of concious visual experience pertaining to the right side of visual information.
What is the difference between Retinotopic and Tonotopic organisation?
Retino: refers to vision, where things objects are in the world matters
Tono: refers to hearing, frequency and amplitude matters
What does cortical cell density in the in the primary visual cortex relate to?
More cells are devoted to the fovea than periphery.
More ganglion cells from fovea needs more cells to process.
What do cortical collumns in the PVC represent?
Each processes a small region of space. When tiled together that represent the entire visual feild. Orientation sensitivity emerges.
Broadly explain the receptive feild of LGN cell.
Light falls on a region of the retina which has a cluster of photoneuron receptors. These are arranged so that that particular pattern of light might have an inhibitory or excitatory affect. Position of object/light pattern matters.
What is the function of simple cells?
Simple cells are essentially configurations of photo cells sewn together. These simple cells will activate when external stimuli is orientated in a similar way
What does orientation selectivity or turning refer to?
How the orientation of objects activates simple cells with an analagous configuration of photoneuron receptors.
What is the PVC also know as?
V1. Here, information is then passed to range of other moduals.
Overview of a hierarchical feed forward model.
This refers to the a hierachy of visual processing. Starting with V1 (orentation), and becoming more and more specific.
What is the difference between dorsal and ventral stream.
Proposed by Milner and Goodale
Dorsal : Where objects are in particular location in the world.
Ventral : *What** object and visual identification .
Which modual is most assoicated with colour processing?
V4.
Concious visual experience.
Difference between parvocellular, and Koniocellular neurons?
Parvo: responsible for red - green
Konio: responsible for blue and - yellow
Much like the inhibition / excitatory bullseye of a photoneuron, how does this work for colour?
There are oppoent cells. Meaning that red stimuli will inhibit green colour. Yellow stimuli will inhibit blue colour.
What are the pairings of opponent ganglion cells.
Yellow - Blue
Red - Green
What is the difference between damage to a colour cone in one eye, and damage to V4 in one hemisphere?
Missed a photoreceptor colour cone in one eye = colour deficency that exends accross the entire visual field
Damage to V4 in one hemisphere = half of our visual experience is colour
What is Achromatopsia? Why is it unlikely?
This is partial loss of colour perception. This is unlikely because damage to V4 without damange to other moduals is unlikely.
Just colour.
What modual is important for our experience of motion?
V5 / MT
What is the difference in movement processing between LGN processing, V1, and V5/MT.
LGN (specifically mangocellular): registers patterns of light and movement but not with any specificity.
V1: responds to movement of bars or edged with specific orentation.
MT: Cell that respond to movement in a particular directio (left to right).
What is the medial-superior-temporal (MST) responsible for?
- Optic flow (self motion = world motion)
- Complex motion
- Biological motion
As seen in monkeys
What is Akinetopsia? How does it occur?
- Motion blindness.
- Bilateral damage to MT.
Example patient LM: see movement in frames.
